TWiki Release 4.0 (Dakar)

Note: This is the release note for the previous major release version 4.0.X. It is included with 4.1.X because it contains valuable information for people upgrading from earlier versions. Both for the admin and the users. See TWikiReleaseNotes04x01 for the 4.1.X release notes

'Dakar' is the first major release of the TWiki Enterprise Collaboration Platform in over a year. The focus of this release has been on refactoring the code in the interests of security, efficiency and maintainability, though a range of powerful new features are also included. The refactoring work has included tightening up the specification of certain key TWiki behaviours, which has resulted in some specification changes. The impact on end users has been minimised as far as possible.

Major New Features

Much simpler install and configuration

Integrated session support

Webserver-independent login/logout

Security sandbox blocks all possible routes for remote command execution on the server

New editing model allows freer collaboration, without fear of overwriting other people's changes

Multilingual UI

E-mail confirmations for registration

WYSIWYG editor

Hierarchical sub-webs

See feature list at TWikiHistory#DakarRelease. TWiki 4.0 patch release details are at the end of this release notes document.

Note: In what follows, {This} (words in curly braces) refers to settings in the new 'configure' interface.

Notes for end users

Editing at the same time as other people

Dakar release introduces a brand-new strategy for handling simultaneous changes to a topic by several people. Instead of one person locking the topic, and other having to wait until they are finished, Dakar allows multiple simultaneous edits of the same topic, and then merges the different changes.

You probably won't even notice this happening unless you are changing existing text in the file at the same time as someone else. In this case, you may see TWiki inserting "change marks" into the text to highlight conflicts between your edits and another persons. These change marks are only used if you edit the same part of a topic as someone else, and they indicate what the text used to look like, what the other person's edits were, and what your edits were. For example, let's say you have a topic that contains this text:

You edit

You see

Casablanca is
Humphrey Bogart's finest film.
Of all the gin joints in all the world,
you had to walk into mine.

Casablanca is
Humphrey Bogart's finest film.
Of all the gin joints in all the world,
you had to walk into mine.

and you start editing this text before going for coffee. Meanwhile, a colleague also starts editng the same topic and changes the text to:

The Maltese Falcon is
Humphrey Bogart's finest film.
Of all the gin joints in all the world,
you had to walk into mine.

The Maltese Falcon is
Humphrey Bogart's finest film.
Of all the gin joints in all the world,
you had to walk into mine.

When you get back from coffee, you finish your edit, changing the text to

To Have or Have Not is
Humphrey Bogart's finest film.
You know how to whistle, don't you Steve?
You just put your lips together and blow.

To Have or Have Not is
Humphrey Bogart's finest film.
You know how to whistle, don't you Steve?
You just put your lips together and blow.

and saving it. The topic will now look like this when you display it:

<div class="twikiConflict"><b>CONFLICT</b> original 5:</div>
Casablanca is
<div class="twikiConflict"><b>CONFLICT</b> version 6:</div>
The Maltese Falcon is
<div class="twikiConflict"><b>CONFLICT</b> version 7:</div>
To Have or Have Not is
<div class="twikiConflict"><b>CONFLICT</b> end</div>
Humphrey Bogart's finest film.
You know how to whistle, don't you Steve?
You just put your lips together and blow.

CONFLICT original 5:

Casablanca is

CONFLICT version 6:

The Maltese Falcon is

CONFLICT version 7:

To Have or Have Not is

CONFLICT end

Humphrey Bogart's finest film.
You know how to whistle, don't you Steve?
You just put your lips together and blow.

As you can see, your changes have been merged with your colleagues. The merge is done on a line-by-line basis, and if your changes do not overlap, then change marks will not be used (as is the case for the last line of the example).

Merging only applies to text fields. When there are conflicts in field data in forms such as checkboxes, radio buttons and selects, the most recent change (usually your change) always wins, even if someone else has changed the form since you started editing. Of course, all changes are available from the topic history.

Because there are cases where you actually want to avoid overlapping edits altogether (e.g. if you are changing forms data) TWiki will warn if you attempt to edit a topic that someone else is editing. It will also warn if a merge was required during a save.

User Interface Internationalisation

TWiki will now pick up the language you are using in your browser, and try to present system messages in that language, if it is available. If your preferred language is not available, TWiki will revert to English. You'll also have an option to choose a language different from that used in your browser.

User Interface Internationalisation support is optional and enabled by the {UserInterfaceInternationalisation} setting.

The translation is performed by the Perl standard internationalization framework. If you want to contribute a new language, it would be most welcome: see TWiki:Codev.UserInterfaceLocalisation for instructions on how to help.

New options on the editing screen

You will notice a couple of changes to the editing screen: first, there is no switch for releasing the edit lock any more (if locks are enabled, they are always released when an edit finishes). You will also notice a new "force new revision" checkbox. TWiki normally doesn't add a new revision if the same user re-edits a topic within a certain time period; this checkbox allows you to force TWiki to add a revision for every change, regardless of how small it is.

Change notification

You now have much more control over which topics in a web you are interested in changes to. You can choose to receive notifications about topics selected by name, or by their parent relationship. See MailerContrib for more details. Note that the mailnotify cron script has moved out of the bin directory and into the tools directory - active crontab entries needs to be updated accordingly.

E-mail addresses

Because of the security risks inherent in publishing e-mail addresses in personal topics, the storage of user's emails has been moved to the password manager. For sites that use the .htpasswd password manager, e-mail addresses that new users provide during registration are stored in the .htpasswd file. To aid in migration, if TWiki can't find a registered e-mail address in .htpasswd, it will still look in the personal topic. All users should register a valid e-mail address at ChangeEmailAddress.

If a different password manager is in use (e.g. LDAP, or 'none'), user e-mails will still be stored in personal topics. Sites that use other password systems (such as LDAP) should consider implementing a TWiki password manager, so that TWiki can look up email addresses, rather than storing them in personal topics.

Parameterised Includes

%INCLUDE{}% variables have a predefined set of parameters. In the past, any parameters not in this set were simply ignored. With Dakar, these parameters are now defined as TWikiVariables within the included topic - for example,

%INCLUDE{ "BugList" FAVOURITE="Damsel Flies" }%

will define %FAVOURITE% as Damsel Flies in the included topic, so if BugList contained the line

My favourite bugs are %FAVOURITE%

it will be expanded to

My favourite bugs are Damsel Flies

Named Section Include

The %INCLUDE{}% variable allows to include only a named section of the included topic. These sections are defined in the included topic using the %STARTSECTION% and %ENDSECTION% variables. For example, if the included topic has:

RSS Feeds

RSS feeds have been enhanced to display links as links to make the feeds more useful. They also now use the web-specific logos.

Notes for TWikiAdmins and WikiMasters

Upgrading

See TWikiUpgradeGuide for help in upgrading an existing Cairo (Sep 2004) installation.

Security

Dakar Release introduces the use of 'safe pipes' to prevent any malicious request from executing code on the server. This strategy stops any of the known attacks dead in its tracks. The Dakar codebase has not been impacted by any of the recent security advisories in any way. Several public sites have been running Dakar code for some months now, and to the best of our knowledge none has been hacked.

Installation and configuration

setlib.cfg

The installer should now provide a file called LocalLib.cfg that contains local path settings. setlib.cfg contains documentation of what has to be done. Old setlib.cfg files will not work with Dakar.

TWiki.cfg

TWiki.cfg now contains all the default configuration settings, and the installer should provide a file called LocalSite.cfg that contains just those settings that are different than the defaults. The syntax of the settings in the file has also changed. Old TWiki.cfg files will not work with Dakar. The UpgradeTWiki script can be used to automate most of the necessary changes.

testenv / configure

testenv has been removed, and replaced with the new configure interface. This interface performs all the checking functions of the old testenv, adds several new ones (including permissions checks) and also acts as a browser interface allowing you to do all TWiki configuration from the browser. configure is now the main installation interface for TWiki.

The configure script can be used like the old testenv for public review of the configuration of the site. Saving from the interface is password-protected, using a password set in the configuration files, so to ordinary users configure just looks like a posh version of testenv. If you want to hide your configuration from public view, you can restrict access to the script using webserver access controls (Apache users see the Apache documentation on the 'require' directive for more infomation on how to do this).

configure optional features

New optional features include {AutoAttachPubFiles} and {EnableHierarchicalWebs}. Both are switched off by default but can be enabled in configure.

Improved support for shorter URLs

Preferences

There have been some significant changes to the handling of preferences, aimed at making them more logical, consistent and easy to use.

Changes to the evaluation order

The rules for preference evaluation (whether the user setting overrides the topic setting etc) have
always been a bit confusing and difficult to use. For example, a topic setting would override a user setting, but
a user setting would override a web setting, making per-web settings awkward to use. Mainly due to the introduction
of hierarchical webs, preferences are now evaluated in the following order:

This is a change from previous versions, where the User preferences were evaluated between the topic and the web.

Note that a user can still dictate preference values that can't be overridden by the topic or the web
level settings, but they will now need to set those preferences as FINALPREFERENCES.
You can use %ALLVARIABLES% in a topic to get a dump of all preferences set in that context.

Permissions controls are not affected by this change.

Preferences Plugin

TWiki:Plugins.PreferencesPlugin has been included to allow more convenient editing of preferences. This plugin provides input controls, such as menus, radio buttons, and checkboxes to select preference settings.

{LocalSitePreferences} (was Main.TWikiPreferences)

Customized site preferences can now be saved in the {LocalSitePreferences} topic which will override settings in {SitePrefsTopicName}. This simplifies upgrades as you can overwrite the {SitePrefsTopicName} topic and gain any new or updated preference settings without losing your local customizations.

FAVICON

favicon.ico is a small graphic that can appear in a variety of places in the browser: the titlebar, the taskbar, the address bar, bookmarks/favourites, and page tabs. Each web browser has a unique user interface, and as a result uses the Favicon in different ways. Most browsers display it in most of the locations listed.

Out of the box, TWiki is configured to easily customise the favicon.ico for each web. To switch to a new favicon.ico, upload it to the desired web's WebPreferences.

Set FAVICON = /twiki/pub/TWiki/WebPreferences/favicon.ico

To provide a single, site-wide favicon.ico, hardcode a specific web, for example:

Set FAVICON = /twiki/pub/TWiki/WebPreferences/favicon.ico

FORCENEWREVISIONCHECKBOX

Normally, if you make another edit within a one hour period (was $editLockTime in lib/TWiki.cfg, now {ReplaceIfEditedAgainWithin}), TWiki will fold together your changes. This is often the "right thing to do", as it can reduce the visual clutter of diffs.

The "Force New Revision" checkbox is a way to force it to create a separate revision each time you save.

The TWiki.TWikiPreferences variable FORCENEWREVISIONCHECKBOX controls whether this is checked by default or not.

On a related note, you can force every save to be a new revision number by editing lib/TWiki.cfg and setting {ReplaceIfEditedAgainWithin} to 0.

NOTE: Although this feature is being introduced in this release, it is also being deprecated at the same time. TWiki:Codev.EdinburghRelease is planned to provide the ability to elide revisions at the GUI level, rather than the Store level, thus obviating the need for this stopgap measure.

WEBLOGONAME, WEBLOGOIMG, WEBLOGOURL, WEBLOGOALT

Each web can have its own customised logo. The simplest way is to upload a logo.gif to a web's WebPreferences, and it will appear in the top-left corner.

To change the logo's filename, set the WEBLOGONAME variable. You'll especially need to do this if you use a different logo file format:

Set WEBLOGONAME = MyLogo.jpg

If you don't want to have custom logos on a per-web basic, but instead want to use a single, site-wide logo, hardcode a specific web in the WEBLOGOURL variable. For example:

Set WEBLOGOURL = %PUBURLPATH%/Main/WebPreferences/logo.png

WIKILOGOIMG, WIKILOGOURL, WIKILOGOALT

These variables are now more closely associated with WIKITOOLNAME. If you change WIKITOOLNAME, you'll probably want to change these variables, too. WIKILOGOIMG, WIKILOGOURL, WIKILOGOALT, and WIKITOOLNAME are now used more consistently together.

Final Preferences

The FINALPREFERENCES setting prevents particular preference settings from being over-ridden at a lower level. The hierarchy of how FINALPREFERENCES settings are applied has been clarified/formalized as reflected in the following chart:

By default, the site level FINALPREFERENCES are set in Main.TWikiPreferences so as not to conflict with preference settings in that topic.

mod_perl support improvements

TWiki no longer uses global variables other than for constants. Each CGI script creates a new "session object" that holds all session-specific information.

There is still an issue with the @INC path in mod_perl, that mainly impacts plugins that lazy-load modules. You should use the PerlSetEnv directive that mod_perl provides to make sure that your TWiki lib directory is permanently on the path, if you are using mod_perl.

Plugins

Plugins are no longer searched for every time a TWiki script is run. Instead they are automatically discovered in configure. To enable and disable plugins, use the configure interface. The entire @INC path is searched for plugins, so you can easily point at plugins outside the installation. However only the first instance of a plugin on the @INC path will be found (it is a path, after all).

%INSTALLEDPLUGINS% and %DISABLEDPLUGINS% are no longer supported in TWikiPreferences. If you have set %INSTALLEDPLUGINS% in TWikiPreferences, you need to move that setting into the {PluginsOrder} configuration key, using the configure interface. To disable plugins, uncheck them in the configure interface, and save the changes.

Whenever you install a plugin, make sure you check TWikiPlugins#FAILEDPLUGINS. Several handlers have been deprecated, and updates of the plugins may be required. Contact the plugin author directly to get an update if none is available on the web.

Logins, Logouts, Sessions and Passwords

TWiki:Plugins.SessionPlugin and TWiki:Plugins.AuthPagePlugin have been integrated into the core. TWiki now supports cookied sessions, in the context of a much improved authentication architecture. The setup for authentication is now much simpler, and for most sites can be done entirely from the configure interface. There are some incompatibilities with TWiki:Plugins.SessionPlugin, with resepect to the in-line variables. See TWikiUserAuthentication in the release for full details of how authentication works now. TWiki also now supports the concept of pluggable password managers, making the integration of corporate authentication services much simpler.

Administrators, especially of public sites, need to be aware of the security implications of cookied sessions, and the potential risks of cross-site scripting attacks that may be used to steal user sessions. See TWikiUserAuthentication for more details.

Protections

The evaluation of protections has been re-worked to make it more naturally understandable, and also fill a number of holes in the protection scheme, These holes meant that it was relatively easy to deny access to a topic, but rather difficult to subsequently restore access without either compromising other topics, or compromising old revisions.

When deciding whether to grant access, TWiki now evaluates the following rules in order (read from the top of the list; if the logic arrives at PERMITTED or DENIED that applies immediately and no more rules are applied). You need to read the rules bearing in mind that VIEW and CHANGE access may be granted/denied separately.

In addition, permissions set on a specific revision of a topic now always apply to that revision, even if access to the topic is relaxed in a later revision. This change was necessary to prevent accidentally permitting access to sensitive data in old revisions.

The major impact of this change is that WebPreferences topics shipped with earlier releases of TWiki will have excessively restrictive controls, as the default settings were:

Set DENYWEBVIEW =

Set ALLOWWEBVIEW =

This will now deny view access to everyone not in the list (i.e. everyone except admins)

Set DENYWEBCHANGE =

Set ALLOWWEBCHANGE =

This will now deny change access to everyone not in the list (i.e. everyone except admins)

Set ALLOWTOPICCHANGE =

This will now deny change access to everyone not in the list (i.e. everyone except admins)

The standard webs shipped with this release have these settings disabled. However you are likely to have inherited the old default settings in your user webs. The easiest way to deal with this is to simply insert a # sign in these settings; for example:

#Set DENYWEBVIEW =

#Set ALLOWWEBVIEW =

etc

Note: For security reasons, the Trash web is shipped with ALLOWWEBVIEW set to empty (so it is only viewable by admins).

Frustrating Robots and Spammers

Standard TWiki incorporates some simple measures to protect e-mail addresses and control the activities of benign robots. These should be enough to handle intranet requirements. Administrators of public (internet) sites are strongly recommended to investigate the TWiki:Plugins/BlackListPlugin.

New User Registration

The new user registration process has been extensively reworked to improve usability and security of the registration process.

E-mail addresses

E-mail addresses for new users are no longer stored in home topics. Instead, the password manager API has been extended to support storing e-mails.

The default password manager stores e-mails in the .htpasswd file - you can safely edit this file with a text editor to modify the info field that contains the e-mail addresses (the format of each line in this file is <username>:<password>:<info>, and TWiki expects the info field to be a ;-separated list of e-mail addresses). Password managers for other systems e.g. LDAP can esily be extended to support the new API. If the password manager does not have an e-mail address for a user, then TWiki will still look in the users' personal topic.

The script tools/upgrade_emails.pl can be used to extract e-mail addresses for existing TWiki users from personal topics, and add them to the password manager.

You are strongly recommended to run this script if you are running a public site.

It will not modify existing personal topics.

The script will tell you if any users are found that don't have an e-mail.

You can re-run the script as many times as you like; once the password manager has an e-mail for a user, the e-mail in their personal topic is ignored.

You should also advise all your registered users to make sure they have a valid e-mail. They can do this by logging in and visiting ChangeEmailAddress.

Change notification support

The old mailnotify script has been retired in favour of the MailerContrib. See MailerContrib for information about functional changes.

What's a Web

Old versions of TWiki would consider all subdirectories of the TWiki data directory to be webs. This behaviour has changed; now only subdirectories that contain a web preferences topic (WebPreferences.txt) will be considered to be webs. This may result in directories that used to return search matches no longer doing so.

Disable <script> tags

In recognition of security concerns around <script> tags, the administrator has the choice whether to allow users to add script to topics or not. See the {AllowInlineScript} setting in the Security section of configure.

Notes for TWikiApplication Developers

Space/Tab conversion

Previous TWiki versions would automatically convert three spaces at the start of lines to a tab when the topic was saved. This meant that the saved topic was not the same as the edited topic, which could result in considerable confusion. This conversion has been disabled, and the saved topic is now exactly what you see in the editor. One impact of this change is that any add-on scripts you may have developed that rely on bulleted list lines starting with a tab will no longer work. They must be adapted to treat groups of three spaces and single tabs as equivalent.

Evaluation order of TWikiVariables

In previous TWiki versions the evaluation order of %VARIABLE%s depended on where they were expanded in the code. The parser was somewhat crude, and could easily be confused when embedded variables (variables embedded in the parameters of other variables) were used.

The parser has been replaced in Dakar with a deterministic variable parser with predictable behaviour. Specifically, variables are now always evaluated left to right and inside out. For example, consider %VAR2{ "%VAR1{ "%VAR0{ "params" }%" }%" }% %VAR3%. Previously, the expansion order would have depended on the order of expressions in the code, so the expansion may have proceeded VAR3 - VAR0 - VAR2 - VAR1. If you were lucky, this was the intended order. In Dakar, the order is now guranteed to be VAR0 - VAR1 - VAR2 - VAR3 (i.e. inside out and left to right).

The main impact of this is that some TWikiApplications may cease to work if they have been written to take advantage of the old chaotic order. There is no way to predict which will work and which will fail, so you will have to deal with this on a case-by-case basis. In most cases TWikiApplication authors will have worked hard to do the "sensible thing" so instances of this problem should be rare.

Note that because the TWiki spec allows double quotes within double-quoted strings in certain variable parameters it has been impossible to make the parser 100% deterministic. There may still be pathological cases where the parser may fail. In these cases, consider how open and close curly brackets are matched up.

Encoding of form-field values

The encoding used to escape characters in form-field values has had to change. The old encoding could very easily be confused by text strings in data values. Existing topics with the old encoding will still be loaded into TWiki as before, but if edited they will be saved with the new encoding. This should not affect you unless you have searches that look for the old encodings; specifically, the %_G_%, %_Q_%, and %_P_% character sequences. Any such searches will not work any more, and need to be converted to search for the new encoding. Assuming they are regex type searches, you can use (%_G_%|%0A) to match encoded newlines in field data in both old and new format topics, (%_Q_%|%22) to match quotes, and (%_P_%|25) for percent signs.

<script> tags in topics

Previous releases of TWiki would attempt to interpret the content of <script> tags in topics as TWiki formatting language, often resulting in non-functional scripts. This release protects script sections from expansion by TWiki. Note that this means that TWikiVariables will not be expanded in script tags - they are passed through verbatim.

In recognition of security concerns around <script> tags, the administrator has the choice whether to allow users to add script to topics or not. Check the setting of {AllowInlineScript} in configure to see if it is allowed on your site. If not, script sections will simply disappear from topics.

<verbatim> tags in topics

Previous releases required verbatim tags to be on their own line. TWiki can now deal with inline verbatim blocks such as

blah<verbatim>inside</verbatim>after

results in

blah

inside

after

NOTE: VARIABLES are still Set within verbatim tags (this is a historical peculiarity)

ALLVARIABLES

You can use %ALLVARIABLES% in a topic to get a dump of all variables set in that context. Invaluable for debugging those tricky TWikiApplications!

IF

The new %IF()% variable defines simple conditional statements that are evaluated at view time. This allows you to include content conditionally based on environmental factors. See IfStatements for more information on usage.

New $count(reg-exp) variable in Formatted Search

This new variable for FormattedSearch returns the number of instances a specified RegularExpression occur in a topic. This is useful for such things as counting the number of comments on a page (assuming they are marked my a unique heading level).

Notes for Skin Developers

Skin search path

Earlier releases of TWiki only allowed for a single skin, so customising a single template in a skin meant deriving a whole new skin. Dakar introduces the concept of a skin search path, which lets you combine skins additively. For example, you can customise just the view template by defining a new view.mylocalskin.tmpl and then setting

Set SKIN = mylocalskin,pattern

Since you have defined a view template for mylocalskin, it will be picked up when you view a topic because mylocalskin is first on the search path. But you didn't define edit.mylocalskin.tmpl, so when you edit the next skin on the search path will be used instead (in this case edit.pattern.tmpl). You can put as many skins on the search path as you like.

As with older releases, setting SKIN (or the skin parameter in the URL) replaces the existing skin path setting. Dakar supports extension of the path as well, using covers.

Set COVER = mylocalskin

pushes a different skin to the front of the skin search path. There is also an equivalent cover URL parameter. For example, /twiki/bin/view/TWiki/WhatIsWikiWiki?cover=print.pattern. This gives you an extra level of flexibility when defining skins.

Supporting web names that are WikiWords

Skins should be upgraded if they have standalone %WEB% variables; only standalone %WEB% text that potentially could be turned into a link (because of a WikiWord) needs to be escaped. Same for %MAINWEB% and %TWIKIWEB%.

Examples:

%WEB% -- needs to be escaped with <nop>%WEB%

(%WEB%) -- needs to be escaped because of parenthesis

"%WEB%" -- no need to escape, does not get linked

<b>%WEB%</b> -- no need to escape, does not get linked

%WEB%.%TOPIC% -- no need, is a Web.TopicName

(%WEB%.%TOPIC%) -- no need, is a Web.TopicName

Basically, any prefix other then space and parenthesis needs to be looked at. %WEB% in a %SEARCH% should not be escaped.

Deprecation of %EDITTOPIC%

In Cairo release (and earlier) the only way to have an edit link that changed with the context was to use %EDITTOPIC%. This was only available in view templates, and had no flexibility in formatting. It was also impossible to disable other active links, such as Attach.

Dakar release includes new support for "context if" parameters to the %TMPL:P% construct. See TWikiTemplates for details. The default templates shipped with Dakar have been modified to use this support. %EDITTOPIC has been deprecated, though it is still available as a simple edit link, defined in TWikiPreferences. Skin authors are strongly recommended to replace this link with context-if conditionals.

Template Parameters

%TMPL:P% now accepts parameters. Values passed in these parameters will be expanded when the %TMPL:DEF% is instantiated. See TWikiTemplates for full details. (Remember, this happens at template expansion time, which is usually very early in the rendering process.)

HTTP and HTTPS

These two new TWikiVariables give access to the HTTP headers sent by your browser. For example, your browser says your browser is %HTTP:{"User-Agent"}% (this will be filled in if you are running Dakar).

QUERYSTRING

This new TWikiVariable gives access to the full query string from the URL sent to your browser. For example, for the URL /twiki/bin/view/TWiki/TWikiReleaseNotes04x00?make=Reliant&model=Robin, the query string is ?make=Reliant;model=Robin (yes, the semicolon is correct!)

Notes for Plugin Developers

Changes to variable parsing

In earlier TWiki versions there was considerable confusion over the syntax and semantics of Preferences, TWiki Variables, and Plugin variables. The documentation suggested that all %VARIABLES% were equal, but in fact some were more equal than others.

The syntax and semantics of preferences and TWikiVariables has been made consistent. %VARIABLE% has been made semantically identical to %VARIABLE()%, so if you set a preference named %VARIABLE% it will automatically be instantiated in place of %VARIABLE{}%. This is an elegant solution in several ways: first, it allows an administrator to electively disable TWikiVariables, simply by defining an overriding preference. Second, it rationalises the semantics in line with the common syntax. Third, it allows a single parser to do all the work, allowing localised optimisation. Fourth, it prevents a plugin from accidentally kidnapping system TWikiVariables (while this can still be done by registering a tag handler, it's a much more explicit process). Fifth, the ground rules are set for a possible future extension to support parameterised TWikiVariables e.g.

Internals

A lot of the TWiki internals have changed. As a result, plugins that bypass the TWiki::Func API and call core functions directly are unlikely to work.

The restructuring of the code internals is such that there are no 1:1 equivalents for the old core functions. Only the TWiki::Func API is guaranteed to work.

You should convert your plugins to call the TWiki::Func API. If you have called unpublished functions that have no equivalent in TWiki::Func, then you may still be able to call the function via the TWiki "session" object, $TWiki::Plugins::SESSION. See the implementation of the TWiki::Func module for ideas on how to do this. However calling internals is not recommended, even using this new mechanism, as they are liable to change without prior notice.

Extensions to the Func API

The TWiki::Func API has been extended to expose a number of new core functions. Review TWikiFuncDotPm for details.

The TWiki::Meta API, which was previously for internal core use only, has now been exposed and may be used in plugins. See TWikiMetaDotPm for full details.

Plugins which observed the existing published API (TWiki::Func) should continue to work.